fix: default config = chat (system/user/assistant cols) for Studio role auto-map

fix: default config = ShareGPT conversations (auto-detect); text/messages as alternates

fix: add default config (ChatML) for unsloth SFT; keep messages/sharegpt; train/validation splits

Update README.md

Convert to Parquet (zstd): default + sharegpt, 2504 records (2254/250)

Replace with +4/command topup: 2504 records (train 2254 / val 250), 329/329 cmds 4-9 ex

Add ubs tool-use CoT dataset: messages + sharegpt formats (1259 records, 329/329 commands)

initial commit